Electrically conductive balloon catheter

ABSTRACT

A balloon catheter having a mesh affixed thereto. The mesh is formed having members extending longitudinally and circumferentially about the balloon into columns and rows respectively. Each member of the mesh has a resistance or impedance that changes as the member is deformed such that, when the member comprises a length (L) a measured resistance or impedance will be different than when the member comprise a length (L 1 ) where L 1  is greater than L.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §119 (e) ofthe U.S. Provisional Patent Application Ser. No. 61/472,950 filed onApr. 7, 2011, which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a system and method for visualizing andmeasuring the interior of a body cavity and more specifically, relatesto visualization and measurement of a body cavity with a ballooncatheter by measuring the electrical characteristics of an inflatedballoon in the body cavity.

BACKGROUND OF THE INVENTION

Balloon catheters are used for various medical procedures. For example,it is known to insert a balloon catheter into a passageway for dilationof the passageway such as is used in interventional bronchoscopy for thetreatment of lung cancer and oft times, the resultant airwayobstruction(s) that occur. Accordingly, balloon catheters have beenroutinely used with various endoscopes and with flexible and rigidbronchoscopes for dilation, as a tamponade to stop bleeding, and as aninterference fixation device to hold instruments in place and preventthe retropulsion of those instruments under backflow pressure.

It is also known to use balloon catheters for removing undesirablebiological material in bodily cavities. For example, inflatable ballooncatheters may be employed as interventional tools for the excision andremoval of unwanted materials—such as endoluminal obstructions andtumors and endovascular occlusions—in various applications, such as theinterventional medical specialties of pulmonology, cardiology, urology,gynecology, gastro-enterology, neurology, otolaryngology, and generalsurgery. An example of such a device is disclosed in European PatentApplication No. EP 1 913 882 by Karakoca. This device employs a ballooncatheter with a hardening surface, which can be inserted into bodilycavities. After the device is inserted, the balloon is inflated, and theballoon is moved back and forth within the cavity such that thehardening surface resects on the unwanted biological material. Forexample, by pulling out the balloon, debris can be removed.

U.S. Patent Application Publication No. 2010/0121270 by Gunday (the '270application) entitled Resector Balloon System, which is incorporatedherein by reference, provides numerous improvements over Karakoca andrelates to a balloon catheter with a textured surface that is operatedin a pulsing fashion to shave the target material with minimal trauma.The '270 application discloses that a balloon system “is able to providephysiologic feedback to determine intra-lumen diameters.” This isaccomplished in one embodiment by the provision of “a sensor thatdetermines the pressure of the fluid output to the balloon and a sensorthat determines the flow of the fluid output to the balloon.” Finally,the '270 application discloses that “by employing multiple,independently inflatable bladders or sinuses . . . one is able to moreselectively and precisely . . . measure . . . intra-lumen diameters.”

However, the '270 application teaches measuring intra-lumen diameters bymeans of measuring pressure and adjusting the pulsing of the ballooncatheter for resecting accordingly. While this method is very effectivefor resecting target material with minimal trauma (e.g. pressuremeasurement coupled with the pulsing of the balloon catheter), it wouldbe advantageous to utilize a balloon catheter to provide accuraterendering of the interior surface of the cavity. Accordingly, thepulsing of fluid into the balloon catheter as taught in the '270application for resecting, along with the associated control system forcontrolling the pulsing of the pump, would not be needed for such anapplication.

Various imaging systems for visualizing internal structures are known,including, for example, Magnetic resonance imaging (MRI), nuclearmagnetic resonance imaging (NMRI), or magnetic resonance tomography(MRT) and computed axial tomography (CAT) or sometimes shorten tocomputed tomography (CT) scan. While these methods can be very effectiveat visualizing internal structures, the cost associated with thepurchase and use of these machines is relatively high.

In the field of orthopedics it is often difficult, if not impossible, toassess the spatial dynamics between articular surfaces; especially asthe articular surfaces translate in opposition to one another throughouttheir ranges of motion. During arthroplasty procedures, in particular,it would be advantageous to understand the geometries of the articularsurfaces as well as the spaces within the joint in the effort to perfectanatomic restoration and joint kinematics, in general.

It may also be advantageous to use an electrically conductive ballooncatheter within the intramedullary canals of bones. The Orthopedic andTrauma science has long struggled to visualize and measure the innersurfaces of bones in real time. The inability to map bone anatomy hashindered surgeon's ability to appropriately size and implantarthroplasty implants (e.g.—Hip Replacement—Femoral and AcetabularImplants). It has also hindered surgeons ability to assess thedisplacement of fractures and to appropriately size and implant fracturemanagement systems (e.g.—Tibial Rodding and Plating systems).

Intra-cavity mapping is also known, such as is disclosed in U.S. Pat.No. 7,654,997 (Makower et al.). However, while Makower et al. uses acatheter device, it requires the use of an external sensor (apart fromthe balloon) to map and provide a 3-dimensional view of the cavity.(See, Col. 40, I. 64—col. 41, I. 24; FIGS. 7D-7E). This is cumbersome,difficult to manipulate and not practical for relative small cavities(e.g., intravascular measurement).

U.S. Pat. No. 5,752,522 (Murphy) discloses an apparatus for determiningcross-sectional dimensions of body lumens, such as the diameter of ablood vessel. (Abstract). However, while Murphy discloses a design thatincludes a catheter having conductor bands which vary in resistance withballoon circumference (col. 9, II. 13-15), Murphy is limited todisclosing “conductor bands.” This will not provide a 3-dimensional viewof the interior of a cavity, but rather, will only provide across-sectional circumference of a cavity. (See, FIG. 7).

What is desired, therefore, is a cost effective and reliable system andmethod for measuring and rendering internal structures of a body. It isfurther desired to provide a system and method for visualizing andmeasuring internal structures of a body that will not necessarily resectmaterial from the internal structures during the processing of measuringthe structures.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aballoon catheter system and method for visualizing and measuringinternal structures of a body.

It is a further object of the present invention to provide a ballooncatheter system and method for generating a three dimensional image ofinternal structures of a body and/or the spaces in between internalstructures of the body.

It is yet another object of the present invention to provide a ballooncatheter system and method for effectively visualizing internalstructures in very small cavities (e.g., intravascular measurement).

It is a further object of the present invention to provide a ballooncatheter system and method for effectively visualizing and measuring thespaces between and/or within internal structures in very small cavities(e.g., Intra-articular measurement; Intra-cavital measurement).

It is still another object of the present invention to provide a ballooncatheter system and method for visualizing internal structures thatprovides a simple, cost-effective and reliable sensor(s) that generate asignal having a signal format that is robust and can be processed in acost-effective manner.

It is also an object of the present invention to provide a ballooncatheter system and method for visualizing internal structures in a bodycavity that will not resect the internal structures.

These and other objectives are achieved, in one advantageous embodiment,by the provision of an electrically conductive mesh affixed to a ballooncatheter. The balloon catheter may be inserted into the cavity tomeasure and provide a three-dimensional image of the interior of thecavity. As the balloon catheter is inflated and conforms to the innersurface area of the cavity, the electrically conductive mesh isstretched based on the inner surface area of the cavity. This stretchingof the electrically conductive mesh (both in a lateral and alongitudinal direction relative to the cavity) will thereby cause achange in an electrical characteristic of the mesh (e.g., impedance orresistance) affixed to the balloon catheter. This change in electricalcharacteristic(s) may then be used to generate a three-dimensionalrendering of the interior structure of the cavity.

It is understood that precise impedance measurement(s) are widelyavailable and cost-effective. For example, to achieve high measurementaccuracy with relatively low product cost, the signal processingtechnique of Discrete Fourier Transform (DFT) may be used with errorcorrection to the impedance measurements. Software can effectively beused to control signal processing and error correction.

The mesh affixed to the surface of the balloon catheter may, forexample, comprise a fiber mesh. It is contemplated that the mesh may beaffixed to either the outer or inner surface of the balloon catheter. Ineither configuration, the balloon will expand to match the shape of theinterior surface of the cavity.

The fiber mesh may comprise lycra, polyurethane, composite springs, orother appropriate material and will include electrical lines (orstrings) therein that will vary in electrical characteristics dependingupon the stretching or displacement of the mesh. In one example, whenthe electrical characteristic to be measured is impedance, as eachportion of the mesh stretches outward to expand to the inner surface ofthe cavity the catheter balloon is to measure, the impedance of variousportions of the mesh will change (e.g., the greater the stretching ofthe mesh the greater the change in impedance). In this manner, becausethe mesh includes portions that extend longitudinally andcircumferentially about the balloon catheter, the device is able toprovide a complete 3-dimensional view of the interior of the cavity asthe system measures an impedance of each section of the mesh.Additionally, as no additional measurement device is needed apart fromthe balloon catheter itself, the device is particularly well suited foruse in relatively small cavities (e.g., intravascular).

It is still further contemplated that the mesh may, in anotherembodiment, comprise a radio-opaque material such that, when insertedinto a cavity and the balloon catheter is expanded, an external view ofthe expanded balloon catheter may be generated via an imaging device(e.g., the radio-opaque material will clearly show up on an externalscan providing a detailed view of the current configuration of thecatheter balloon. It is contemplated that both the electricalmeasurement of the mesh and imaging of the mesh having a radio-opaquematerial could be used to provide a high-resolution 3-dimensionalrendering or imaging of the interior of the cavity.

For this application the following terms and definitions shall apply:

The term “data” as used herein means any indicia, signals, marks,symbols, domains, symbol sets, representations, and any other physicalform or forms representing information, whether permanent or temporary,whether visible, audible, acoustic, electric, magnetic, electromagneticor otherwise manifested. The term “data” as used to representpredetermined information in one physical form shall be deemed toencompass any and all representations of the same predeterminedinformation in a different physical form or forms.

The term “network” as used herein includes both networks andinternetworks of all kinds, including the Internet, and is not limitedto any particular network or inter-network.

The terms “first” and “second” are used to distinguish one element, set,data, object or thing from another, and are not used to designaterelative position or arrangement in time.

The terms “coupled”, “coupled to”, “coupled with”, “connected”,“connected to”, and “connected with” as used herein each mean arelationship between or among two or more devices, apparatus, files,programs, media, components, networks, systems, subsystems, and/ormeans, constituting any one or more of (a) a connection, whether director through one or more other devices, apparatus, files, programs, media,components, networks, systems, subsystems, or means, (b) acommunications relationship, whether direct or through one or more otherdevices, apparatus, files, programs, media, components, networks,systems, subsystems, or means, and/or (c) a functional relationship inwhich the operation of any one or more devices, apparatus, files,programs, media, components, networks, systems, subsystems, or meansdepends, in whole or in part, on the operation of any one or more othersthereof.

The terms “process” and “processing” as used herein each mean an actionor a series of actions including, for example, but not limited to, thecontinuous or non-continuous, synchronous or asynchronous, direction ofdata, modification of data, formatting and/or conversion of data,tagging or annotation of data, measurement, comparison and/or review ofdata, and may or may not comprise a program.

In one advantageous embodiment an imaging system for providing a3-dimensional image of the interior of a cavity is provided comprising:a balloon catheter and a mesh affixed to the balloon catheter, the meshhaving members extending longitudinally and circumferentially about theballoon catheter. The imaging system further comprises a controllercoupled to the balloon catheter for controlling the inflation of theballoon catheter. The imaging system is provided such that each memberof the mesh has at least one electrical characteristic that changes asthe member is stretched such that, when the member comprises a length(L) a measured electrical characteristic will be different than when themember comprise a length (L₁) where L₁ is greater than L. The imagingsystem is further provided such that the controller measures the atleast one electrical characteristic from each member and utilizes themeasured electrical characteristics to generate a three-dimensionalrendering of an interior surface of the cavity.

In another advantageous embodiment a balloon catheter is providedcomprising a mesh affixed to a balloon. The mesh includes membersextending longitudinally and circumferentially about the balloon intocolumns and rows respectively. Each member of the mesh has a resistanceor impedance that changes as the member is deformed such that, when themember comprises a length (L) a measured resistance or impedance will bedifferent than when the member comprise a length (L₁) where L₁ isgreater than L.

In still another advantageous embodiment a method for constructing aballoon catheter is provided comprising the steps of forming a mesh byextending members longitudinally and circumferentially to form columnsand rows. Each member of the mesh has a resistance or impedance thatchanges as the member is deformed. The mesh is provided such that when amember comprises a length (L) a measured resistance or impedance will bedifferent than when the member comprise a length (L₁) where L₁ isgreater than L. The method further comprises the step of affixing themesh to a balloon.

Other objects of the invention and its particular features andadvantages will become more apparent from consideration of the followingdrawings and accompanying detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram on one advantageous embodiment of the presentinvention.

FIG. 2 is an illustration of the balloon catheter including the meshaccording to FIG. 1.

FIGS. 3A and 3B are illustrations of the balloon catheter of FIG. 2inserted into a cavity for providing a 3-dimensional rendering of thecavity.

FIG. 4 is a representation of the mesh used in connection with thesystem of FIG. 1.

FIG. 5 is an illustration of the balloon and module according to theembodiment of FIG. 1.

FIG. 6 is molded module an illustration of the module inserted into thetube according to the embodiment of FIG. 5.

FIG. 7 is an illustration of one embodiment of the mesh constructionaccording to FIG. 1.

FIG. 8 is an integrated circuit block diagram according to theembodiment of FIG. 6.

FIG. 9 is a flow diagram of a method according to the embodiment of FIG.1.

FIG. 10 is a continuation of the flow diagram according to FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIG. 1 is a block diagram of anadvantageous embodiment of a system 100 for generating a threedimensional image of an interior of a body cavity 150 (FIGS. 3A and 3B).

The system 100 includes a controller 102, which may comprise any type ofcontroller known in the art for controlling the inflating and deflatingof a balloon 1104 attached thereto by means of a catheter 118 thatincludes electrical lines 130 to communicate with the controller 102.The controller 102 is coupled to an input device(s) 106 that maycomprise virtually any type of interface including, for example but notlimited to, a keyboard, a mouse, a touch screen or touch pad, avoice-activated control input device, etc. It is understood that inputdevice 106 may be either wired or wireless, which is illustrated by theuse of a dashed line and wireless transmission signal indication inFIG. 1. It is still further contemplated that the input device maycomprise a mobile wireless device.

A display 108 is coupled to the controller that may present a visualrendering of the balloon catheter 104 in an inflated state, which may bestored on a storage device 110. A computer 112 (e.g., a personalcomputer) is also shown coupled to the controller 102 via a networkconnection 114. It is contemplated that the computer 112, 112′, 112″ maycomprise a single computer or a network of computers (e.g., a pluralityof hospital computers and associated storage devices, etc.), or a remotecomputer (e.g. in the doctor's office or an offsite location) where animage generated by the deformation of the balloon catheter 104 may bedisplayed and stored in a storage 116, 116′, 116″.

The rendering is a 3-dimensional rendering of the volume of the cavity.In one embodiment, the user may, by means of an input device, rotate thedisplayed 3-dimensional rendering to obtain different viewing angles.This allows, for example, the physician to get an extremely accurateview of the interior of the cavity. It may be desired to render theinterior of the cavity, then, resect material from the cavity andgenerate a second rendering of the cavity after resection. This processcould be performed in numerous stages. However, the system provides theability to freely rotate the rendering allowing the user to view thevolume surface of the cavity from virtually any viewing angle andmagnification.

Referring now to FIG. 2, the balloon 1104 connected to the controller102 by means of the catheter 118 is shown in greater detail. Thecatheter 118, may comprise, for example, a polyethylene material andhaving an outer diameter of 0.5 mm-2 mm and a length of about 1.2 to 3meters. The catheter is typically flexible such that it may be insertedinto a cavity and may follow the course of the cavity freely withoutcausing harm to the cavity (e.g., freely bendable to follow the courseof the cavity, but non-compressible axially so that it may be insertedinto the cavity). One example of an elongated body cavity would beinsertion into the femoral artery in a patient's thigh, into which thecatheter may be inserted to progress toward the patient's heart.

The catheter 118 may further include a bendable section 120 having alength of about 5 to 10 mm at the distal end of the catheter may serveas a safety tip. This is an advantageous feature because, when thecatheter is inserted through the available opening of a bodily cavity,it will bend instead of puncturing the walls of the cavity.

A balloon 1104 may comprise a compliant material, such as latex,chronoprene, yulex, silicon, polyurethane, C-flex or any other suitablematerial and is typically positioned near a distal end 122 of thecatheter 118 or at an otherwise desirable, predefined distance along thecatheter 118. The balloon 1104 may come in a variety of lengths anddiameters, which can be selected to suit the particular application forwhich the device is being used. Typically, such balloons 104 will havelengths selected from: 5 mm, 10 mm, 15 mm, 20 mm, 30 mm, 50 mm orgreater. Such balloons 104 will also typically have diameters selectedfrom: 2.5 mm, 5 mm, 10 mm, 15 mm, 20 mm, 30 mm or 50 mm or greater. Thisvariety of available balloon sizes allows the balloon 104 to be used inbodily cavities of various diameters and dimensions, such as withinarticular joints (e.g., knee) or organs (e.g. Bladder) or within largeand small bronchial branches, sinuses, and vessels, having differentgeometries and/or types of tumors and tissues to be treated. Thecontroller 102 (which may include a pump 124, FIG. 1) supplies fluid(e.g. air, etc.) at a pressure ranging from approximately ½ atmosphereto approximately 6 atmospheres in order to be able to inflate theballoon 1104 to maximum size, ranging from 2.5 mml to 50 mml. It isunderstood that the pressure used to inflate the balloon will depend onthe application. For example, rendering the interior of a bone cavitymay require a higher inflation pressure than rendering the interiorcavity of a blood vessel or artery. When soft tissue is rendered, theinflation pressure will be lower so as to avoid deforming the softtissue.

In certain advantageous embodiments, the balloon 1104 may includeimaging markers 126′, such as radio opaque material or rings, located onthe balloon 1104. Such markers can be selected and appropriatelypositioned in order to reflect the relevant waves of various imagingmodalities (e.g., x-ray) in order to allow the use of such modalities toprovide data so that the system is able to generate a 3-dimensionalrendering of the interior of the cavity. It is understood that togenerate a 3-dimensional rendering, a plurality of x-ray images fromdifferent views would have to be taken and assembled.

The balloon may also be covered with a fiber mesh 126 affixed to thesurface 128 (either exterior or interior) of the balloon (or may beintegral with the balloon). In certain advantageous embodiments, thesurface 128 comprises a textured surface approximately 0.2 mm thick thatis an integral part of the balloon 1104 and which is incorporatedtherein during the molding process. In these cases, the surface 128 ismade by integrating into the balloon material a fine, fiber mesh 126,which can, in certain embodiments, comprise lycra, polyurethane,composite springs, or other appropriate material.

Referring now to FIGS. 3A and 3B, the balloon 1104 and catheter 118 isillustrated inserted into a cavity 150 and expanded to an interiorsurface 152 of the cavity 150. The mesh 126, 126′ is provided such thatupon stretching of the balloon 1104, the mesh 126, 126′ is stretched toconform to the interior surface of the cavity 150. When the mesh 126′comprises a radio opaque material or rings, once inserted and inflated,an imaging device may be used to generate a 3-dimensional rendering ofthe interior of the cavity. For example, if the imaging device is anx-ray, the radio opaque material will reflect the x-ray wave lengthsgenerating the 3-dimensional view of the interior surface of the cavity.

When the mesh 126 comprises a mesh having variable electricalcharacteristics (e.g., impedance or resistance), upon expansion of themesh 126, the variable electrical characteristic(s) will change based onthe extent that the mesh 126 stretches to conform to the interiorsurface 152. Accordingly, as shown in FIGS. 3A and 3B, the mesh willstretch more is some places (both longitudinally and circumferentially)and less in others. The controller 102 will monitor the electricalcharacteristic(s) change(s) in the mesh 126 and will generate an image154 rendering of the interior surface of the cavity 150 based upon thechange in the measured electrical characteristic(s) of the mesh 126.

It is further understood that an imaging device (not shown) may also beused to generate an image of the expanded balloon 1104, which could beused alone or in conjunction with the data generated by the changedelectrical characteristic(s) to generate a 3-dimensional rendering ofthe interior surface 152 of the cavity 150.

FIG. 4 represents the mesh made of elastic conductive material (elasticconductive yarn), which is on an inflated compliant balloon. Theresistance of the mesh 126 changes as it is stretched. Thus thestretched material length is a function of its resistance. The functioncan be linear, exponential, logarithmic, or other. The resistance andchange in resistance based upon specified deformation is based on thecomposition of material, including the amount of conductive fiber (i.e.iron) added thereto. The repeatable function is known in advance.

The rows of the conductive material are illustrated as runningcircumferential to the balloon 1104, while the Columns are theconductive material running lateral on the balloon104.

Also illustrated in FIG. 4, are resistances designated as Rn, which areshown illustrated as boxes representing each segment of conductivematerial as equivalent to a known resistance. The resistances arelabeled according to the nodes 156 they are connected between. Theelectrical resistance value of each segment is a function of the amountthat the conductive material segment has been stretched and thus thelength of the segment.

Each node (represented by, for example, a dot) is a knot 158 (FIG. 7)where the conductive material may intersect. On an inflated balloon 104(e.g., FIGS. 3A, 3B & 5), the nodes 156 are the only place where theconductive material touch each other and create a closed circuit betweencolumns and rows when the balloon is inflated.

Elastic Conductive Yarns:

Elastic conductive yarns are available from various sources and can bemanufactured in many different ways, including coating the elastic yarnwith conductive material (polymers or metallics) or adding metalparticles to the elastomers. In either case the electrical conductivityor the resistance of unit length of the yarn is a function of the amountof stretched. Resistance can be calculated from the following formula:

R=f(ΔI)   Formula 1

This function can be a linear, exponential, logarithmic, etc., but it isknown and given the resistance of a segment of yarn, the length of thatparticular segment may be determined. For example, it is contemplatedthat a look-up table including the various resistance measurements andassociated lengths may be provided in storage 110, 116, 116′, 116″. Oncethe resistance of a particular segment is determined, the actualresistance may be used to determine the length of the segment from thelook-up table. Alternatively, the length may be calculated each time aresistance measurement is taken. An example of one method for generatingan elastic conductive yarn can be seen from the article entitled WovenElectronic Textiles: An Enabling Technology for Health-care Monitoringin Clothing by Christoph Zysset et al., Sep. 29, 2010.

Forming Balloon Sleeve Mesh From Conductive Yarn:

Many techniques can be used to produce the mesh 126 using conductiveyarn similar to techniques used in textile manufacturing, includingweft, warp circular or flat knitting as well as flat weaving creating anetwork of resistors. In case of flat techniques the yarn at twohorizontal ends can be twisted and brought to the vertical top andbottom terminations. In FIG. 7 each end of the XY matrix that is formedis denote by X X′ and Y Y′.

Integrated Circuit:

Referring now to FIGS. 4 and 8, each end 160 of the elastic conductiveyarn is connected to a pin of the integrated circuit 162. Each pin ofthe integrated circuit 162 is tri-state, such that it can be driven: 1)High: the pin is driven to high voltage (i.e. 5V), source current; 2)Low: the pin is driven to low voltage (i.e. 0V/Gnd), drains current; or3) High impedance: the input impedance of the pin is at very high value,does not source or drain current).

There are integrated circuits 162 illustrated in FIG. 4. The integratedcircuits 162 may include multiplexer(s) and de-multiplexer(s), which maybe connected to a computer 112, 112′, 112″ via serial data in 170 ,serial data out 172, clock 174, power 176 and ground 178.

The integrated circuit(s) 162 are provided as a very small packagesuitable to be mounted in a catheter tubing (FIGS. 5 & 6). It iscontemplated that the elastic conductive yarn may, in an advantageousembodiment, be connected or coupled to integrated circuit(s) 162 with aconductive glue.

The timing controller 164 receives commands from a computer 112, 11 ′,112″ via serial communication lines 166, 168 connected to the integratedcircuit 162 at the proximal end. The timing controller 164 providestiming information for driver 166 and scanner 167.

Based on the data received a driver(s) 166 are enabled and the drivesignal (High) is imposed to I/O pin(s), then all other pins are scannedand input to the analog to digital (ND) converter 168.

The digital output of the A/D converter 168 is input into a serializer170 and sent to the computer 112, 112′, 112″ in a serial fashion.

Algorithms for Scanning the Mesh Resistor Networks:

Software controlling the drivers 166, may sequentially activate a singleline of elastic conductive yarn while holding all other lines at highimpedance. Each orthogonal line can, in one embodiment, then be scannedand the voltage measured can then be converted to a digital value.

It should be noted that, while various functions and methods have beendescribed and presented in a sequence of steps, the sequence has beenprovided merely as an illustration of one advantageous embodiment, andthat it is not necessary to perform these functions in the specificorder illustrated. It is further contemplated that any of these stepsmay be moved and/or combined relative to any of the other steps. Inaddition, it is still further contemplated that it may be advantageous,depending upon the application, to utilize all or any portion of thefunctions described herein.

For example, when Col. 1 is driven the equivalent circuit for Row R is:

R(12,RR)+R(23,RR)+R(34,RR)+ . . . +R(C-1 C-1,RR)   (Equation 1)

When Col. 1 is driven the equivalent circuit for Row R-1 is:

R(11,R R-1)+R(12,R-1 R-1)+R(23, R-1 R-1)+ . . . +R(C-1 C,R-1 R-1)  (Equation 2)

And so on.

When Col. 2 is driven the equivalent circuit for Row R is:

R(23,RR)+R(34,RR)+ . . . +R(C-1 C-1,RR)   (Equation 3)

When Col. 2 is driven the equivalent circuit for Row R-1 is:

R(22,R R-1)+R(23, R-1 R-1)+ . . . +R(C-1 C,R-1 R-1)   (Equation 4)

And so on.

The value of resistor R(12,RR) will be the difference between theequations 1 and 2. Similarly, R(12, R-1 R-1)+R(11, R R-1) will be thedifference between the equations 3 and 4.

When scanning is done with the second set of ICs horizontal R(12, R-1R-1)+R(11, R R-1) is resolved and each resistor value is known (FIG. 4).

It is understood that there are a number of different methods that themesh resistor network may be scanned to determine or approximate theresistance of each segment. Some of these methods include: utilizationof Kirchoff's laws, elimination of segment, transfer matrix, Green'sfunction resistance distance, etc.

Surface Mapping

The following symbols are used for surface mapping

-   -   (x, y, t): a (x, y) grid at time t    -   R(x, y, t): a measured resistor value at time t    -   G(x, y, t): four R value measured within a grid at time t    -   Diff(x, y, t): G value difference between time t and t-1    -   T(x, y, t): a transformation matrix derived from G(x, y, t)    -   T′(x, y, t): error corrected transformation matrix from T    -   G′(x, y, t): projected G value from T′(x, y, t-1)    -   E(x, y, t): difference between G and G′ at time t

Let R(<x−1 x>, <y, y>) denotes measured resister value between point<x−1,y> and point <x, y>.

Let G(x,y) denotes four resistors value measured among point<x−b 1,y−1>, point <x−1, y>, point <x, y−1> and point <x, y>.

G(x, y)={R(<x-1, x-1>, <y-1, y>), R(<x-1, x>,<y-1, y−1>) , R(<x-1, x>,<y, y>), R(<x, x>, <y-1, y>)}  (Equation 5)

Let G(x, y, t) denotes as G(x, y) measured at the time t. Let Diff(x, y,t) denotes as resisters value difference between G(x, y, t) and G(x, y,t-1).

Diff(x, y, t)=SQRT((G(x, y, t)-G(x, y, t-1))*2)   (Equation 6)

Let T(x, y, t) denotes a 5×5 transformation matrix between G(x, y, t)and G(x, y, t-1).

G(x, y, t)=G(x, y, t-1)*T(x, y, t)   (Equation 7)

Both G(x, y, t) and G(x, y, t-1) are known values.

INVERSE(G(x, y, t-1))*G(x, y, t)=INVERSE(G(x, y, t-1))*G(x, y, t-1)*T(x,y, t)   (Equation 8)

INVERSE(G(x, y, t-1))*G(x, y, t)=I*T(x, y, t)   (Equation 9)

T(x, y, t)=INVERSE(G(x, y, t-1))*G(x, y, t)   (Equation 10)

Surface Mapping Algorithm.

1. At t=t0

a. save all G(x, y, t0) for [x=1 . . . m] and [y=1 . . . n]

2. From t=t1 to to

-   -   a. for each G(x, y, t)    -   i. Compute Diff(x, y, t);    -   ii. Save the x and y location for the smallest Diff(x, y, t)        value to X and Y;    -   iii. Use Simple Value Decomposition (SVD) algorithm or to solve        T(x, y t) from:

G(x−2, y−2, t) G(x−1, y−2, t) G(x, y−2, t) G(x+1, y−2, t) G(x+2, y−2, t)

G(x−2, y−1, t) G(x−1, y−1, t) G(x, y−2, t) G(x+1, y−2, t) G(x+2, y−2, t)

G(x−2, y, t) G(x−1, y, t) G(x, y, t) G(x+1, y, t) G(x+2, y, t)

G(x−2, y+1, t) G(x−1, y+1, t) G(x, y+1, t) G(x+1, y+1, t) G(x+2, y+1, t)

G(x−2, y+2, t) G(x−1, y+2, t) G(x, y+2, t) G(x+1, y+2, t) G(x+2, y+2, t)

-   -   iv. If (t>t1)        -   1. Compute the projected G′(x, y, t) using T′(x, y, t-1);        -   2. Compute the difference between G(x y, t) and G′(x, y, t)            as E(x, y, t);        -   3. Use Least Square Model Fitting(LSM) algorithm to fit the            E(x, y, t) within [x−9 . . . x+9, y−9 . . . y+9] mesh grids.

3. At t=t3 to tn

-   -   a. Using G(x, y, t-1) and T′(x, y, t-1) and E(x, y, t-1) to plot        the 3D surface as:

G(x, y, t)=G(x, y, t-1)*T′(x, y, t-1)+E(x, y, t-1) at the view port.

This is the equation that is used for generating the rendering fromdifferent viewing angles.

Flexible Electronic Circuitry and Method of Connecting to Conductiveyarn:

Methods of making flexible electronics 184 (including integrated circuit162) suitable for interface with textiles, yarn and treads areavailable. One such method is disclosed in patent U.S. Pat. No.6,493,933.

FIGS. 5 & 6 show one method of molding such electronics 184 inside atubing 180 such that the flexible connection leads 182 extended to theoutside of the tubing 180.

Each end 186 of the tubing 180 is then inserted into the catheter tubingbefore and after the balloon 1104 with the mesh sleeve.

It should be noted that the molded structure 188 that the integratedelectronic circuit 184 is mounted in has holes 190 such that the ballooninflation medium can pass through.

These flexible connection leads 182 expand and contract as the balloon1104 is inflated and deflated.

The desired elastic yarn member (mesh 126) is attached to the leads 182by various methods, including stitching, gluing (conductive), mechanicalcoupling (folding, squeezing, etc.) or combinations thereof.

FIGS. 9 and 10 are a flow diagram illustrating a method for generating athree dimensional rendering of a cavity by measurement of resistorvalues. At step 200, the system measures resistor values in G(x, y, t)and proceeds to step 202 to determine if t=t0. If t=t0, then the systemsaves all measured resistor values 204 in memory 206. If t0≠t0, thesystem determines if t>t1 at step 208. If t≠t1, then the systemcalculates the DIFF(x, y, t) from G(x, y, t) and G(x, y, t-1) at step210, and saves <x, y> for the smallest DIFF value at step 212 in memory206. The system then proceeds to solve T(x, y, t) from G(x, y, t) where[x=x−2 to x+2] and [y=y−2 to y+2] at step 214, which is also saved inmemory 206.

[moo] If t>t1 at step 208, then the system proceeds to step 216 todetermine if t>t2. It can additionally be seen by reference to FIGS. 9and 10 that the system will alternatively proceed from step 214 to step216 to determine if t>t2.

If t≦t2 at step 216, then the system computes the projected G′(x, y, t)using T′(x, y, t-1) at step 218, which is saved in memory 206. Thesystem then proceeds to compute the difference between G(x, y, t) andG′(x, y, t) as E(x, y, t) at step 220. At this point the system uses theLeast Square Model Fitting (LSM) algorithm to fit the E(x, y, t) withinthe mesh window of [x−9 . . . x+9, y−9 . . . y+9] mesh grids at step 222and proceeds back to step 210 to calculate the DIFF(x, y, t) from G(x,y, t) and G(x, y, t-1).

If t>t2 at step 216, then the system uses G(x, y, t-1) and T′(x, y, t-1)and E(x, y, t-1) to plot the 3D surface as G(x, y, t)=G(x, y, t-1) *T′(x, y, t-1)+E(x, y, t-1) at the view port at step 224, which is thensent to display 226.

Although the invention has been described with reference to a particulararrangement of parts, features and the like, these are not intended toexhaust all possible arrangements or features, and indeed many othermodifications and variations will be ascertainable to those of skill inthe art.

1. A balloon catheter comprising: a mesh affixed to a balloon, said meshhaving: members extending longitudinally and circumferentially about theballoon into columns and rows respectively, each member of said meshhaving a resistance or impedance that changes as the member is deformedsuch that, when the member comprises a length (L) a measured resistanceor impedance will be different than when the member comprise a length(L₁) where L₁ is greater than L.
 2. The balloon catheter according toclaim 1 wherein the columns and rows intersect each other at nodes and achange in resistance or impedance between each node may be determined.3. The balloon catheter according to claim 2 wherein said nodes compriseknots.
 4. The balloon catheter according to claim 1 further comprisingan integrated circuit having pins connected to ends of the columns androws.
 5. The balloon catheter according to claim 4 wherein saidintegrated circuit is molded into a tube, which may be affixed to acatheter.
 6. The balloon catheter according to claim 5 wherein saidintegrated circuit includes flexible connection leads that extend outthrough the tube and connect to the ends of the columns and rows.
 7. Theballoon catheter according to claim 5 wherein said integrated circuitcomprises holes such that a balloon inflation medium may pass therethrough.
 8. The balloon catheter according to claim 5 wherein saidintegrated circuit comprises a timing control and a driver.
 9. Theballoon catheter according to claim 8 wherein said integrated circuitfurther comprises an analog to digital converter and a serializer. 10.The balloon catheter according to claim 1 wherein the balloon isselected from a material selected from the group consisting of: latex,chronoprene, yulex, silicon, polyurethane, C-flex and combinationsthereof.
 11. The balloon catheter according to claim 1 wherein said meshis affixed to an outer surface of said balloon.
 12. The balloon catheteraccording to claim 1 wherein said mesh is integrally formed with saidballoon.
 13. The balloon catheter according to claim 1 wherein thechange in resistance or impedance is calculated by R=f(ΔI).
 14. Theballoon catheter according to claim 1 wherein each member comprises aradio-opaque material.
 15. A method for constructing a balloon cathetercomprising the steps of: forming a mesh by extending memberslongitudinally and circumferentially to form columns and rows, eachmember of said mesh having a resistance or impedance that changes as themember is deformed such that, when the member comprises a length (L) ameasured resistance or impedance will be different than when the membercomprise a length (L₁) where L₁ is greater than L; and affixing the meshto a balloon.
 16. The method according to claim 15 wherein the step offorming a mesh further comprising forming a grid such that the columnsand rows contact each other at nodes and a change in resistance orimpedance between each node may be determined.
 17. The method accordingto claim 16 wherein the nodes are formed as knots.
 18. The methodaccording to claim 17 further comprising the step of connecting ends ofthe columns and rows to pins of an integrated circuit.
 19. The methodaccording to claim 18 further comprising the step of molding theintegrated circuit into a tube, which may be affixed to a catheter. 20.The method according to claim 19 wherein the integrated circuit includesflexible connection leads that extend out through the tube and themethod further comprises the step of connecting the ends of the columnsand rows to the flexible connection leads.
 21. The method according toclaim 19 further comprising the step of forming holes in the integratedcircuit such that a balloon inflation lumen can pass there through. 22.The method according to claim 18 further comprising the step ofpositioning a timing control and a driver in the integrated circuit. 23.The method according to claim 22 further comprising the step ofpositioning an analog to digital converter and a serializer in theintegrated circuit.
 24. The method according to claim 15 furthercomprising the step of forming the balloon from a latex material. 25.The method according to claim 15 further comprising the step of affixingthe mesh to an outer surface of the balloon.
 26. The method according toclaim 15 further comprising the step of integrally forming the mesh withthe balloon.
 27. The method according to claim 15 further comprising thestep of calculating a change in resistance or impedance by using theformula:R=f(ΔI).
 28. The method according to claim 15 further comprising thestep of forming each member from a radio-opaque material.